PROJECT SUMMARY/ABSTRACT Cochlear implantation is the standard of care for patients with bilateral severe-to-profound sensorineural hearing loss. Based on changing cochlear implant (CI) indications and increased numbers of adults with hearing loss due to an aging population, the number of adult CIs performed annually continues to increase. CI outcomes are primarily assessed using word and sentence recognition, which, although important, do not capture the diverse listening and communication experiences of CI users. Moreover, outcomes reported using these test batteries are often are poorly correlated with CI user self-report of real-world communication and other abilities. The lack of a universally accepted CI-specific patient reported outcome measure (PROM) to assess functional outcomes and quality of life (QOL) is a critical barrier to further our understanding of the way in which cochlear implantation influences communication, social, emotional, and other experiences of adult CI users. The long term goal of this research is to expand outcomes related to cochlear implantation beyond those narrowly defined by speech recognition, to provide a more comprehensive understanding of how cochlear implantation impacts its users. The overall objective of the current proposal is to determine the impact of cochlear implantation on patient QOL through the application of our new, disease-specific CI-QOL instrument. Our central hypothesis is that CI users not only benefit from improved communication, but also show improvements in social, emotional, and other CI-related QOL domains that together improve their general health-related QOL. Based on compelling preliminary results, our hypothesis will be tested by completing two specific aims: 1) Determine the contribution of patient demographic and hearing-related factors to CI-QOL through the psychometric comparison of the newly developed QOL instrument against legacy measures; and 2) Assess the relationships between CI-QOL domains, functional outcome measures, and general health-related QOL. Aim 1 will be completed through a large population cross-sectional study. In Aim 2, participants will complete the new CI-QOL instrument, functional outcome measures corresponding to the 6 domains of CI-QOL instrument, and a general health-related QOL instrument, before implantation and at intervals throughout the first 12 months post implantation. This work is innovative as it applies a new CI-QOL instrument that has been developed using a theoretical framework and approaches that have never been applied to the adult CI population. Additionally, our longitudinal study is innovative as it evaluates the degree to which each CI-QOL domain relates to functional abilities and the impact of cochlear implantation on general health-related QOL. The results will also provide critical preliminary data for future research aimed at identifying individual patient characteristics that impact CI outcomes, developing patient-specific strategies and rationale for performance improvements (such as new implantation techniques, listening modalities, and processing strategies), and making better estimates of the health utility and economic impact of CIs.